1. Evolution of mechanical heart valves
Richard A DeWall, MD, Naureen Qasim, MD, Liz Carr 
The Annals of Thoracic Surgery 
Volume 69, Issue 5, Pages (May 2000)
DOI: /S (00)

2. Fig 1
(A) The Hufnagel ball valve was developed in 1951 and applied clinically before the availability of heart-lung machines. It was placed in the descending thoracic aorta for patients with aortic insufficiency. (B) The Bahnson fabric aortic cusp valve saw clinical use in Flexible leaflet valves for both aortic and mitral applications composed of either fabric or silicone-covered fabric were tried in the late 1950s and early 1960s by several investigators. The development of heart-lung machines in the mid-1950s made possible the direct approach to valve surgery. (C) A double cage identified the Harken-Soroff ball valve of The outer cage served to separate the valves struts from the aortic wall. (D) The Starr-Edwards ball valve of 1960 continues today in its clinical use. It demonstrated that a double cage was unnecessary. (E) The Magovern-Cromie ball valve of 1962 had a rapid fixation mechanism of multiple curved pins mobilized from the cloth ring of the valve to attach the prosthesis to the native valve annulus. It incorporated an open cage to prevent streamers of clot forming at the junction of crossing struts. (F) The Lillehei-Cruz-Kaster prosthesis in 1963 introduced the tilting disc concept to prosthetic valves. (G) The Gott-Daggett prosthesis of 1963 incorporated a silicone-impregnated fabric disc fixed at its diameter to a polycarbonate ring. The valve was carbon-coated, which led to the development of Pyrolyte carbon used in components of almost all prosthetic valves made from the late 1960s on. (H) UTC-Barnard Aortic Prothesis UTC refers to the University of Cape Town. This modified disc or plunger valve was made in the US.
The Annals of Thoracic Surgery  , DOI: ( /S (00) )

3. Fig 2
(I) In the mid-1960s a number of nontilting disc valves were developed. In 1965 the Cross-Jones caged disc valve contained a disc poppet of silicone rubber reinforced with a titanium ring to add stiffness to the disc. The retaining struts did not meet, forming an open cage. (J) The Smelloff-Cutter prosthesis in 1966 introduced a new concept. With this valve a silicone rubber poppet was sized to seat within the ring of the valve housing, clearing the ring by a few thousandths of an inch. (K) The UCT-Barnard mitral prosthesis first used in 1962 represented an early disc valve concept. The disc was free-floating and retained by a centrally located peg. (L) The Kay-Suzuki disc valve of 1964 had a closed cage and a radiotranslucent disc. Discs in the early models of nontilting disc valves developed notching from rubbing against the struts and became dysfunctional. When Pyrolyte was introduced for poppets in the late 1960s, the notching problem was solved. (M) The Lillehei-Nakib toroidal disc valve in 1967 contained a disc with a large perforation in its center. During the closure the disc would sit on a central spindle sealing the central hold. (N) With the Beall-Surgitool valve in 1967, velour fabric covered the orifice, with a Teflon poppet. As the poppet tended to notch on the parallel struts, Pyrolyte carbon was later used for the poppet. (O) The Davila prosthesis of 1968 incorporated a novel modified disc poppet. The poppet mechanism was a cylinder with one end a closed plate or a disc, which was connected by four struts to a flared ring. During systole the ring would catch the annulus of the prosthetic valve. (P) The flexible fabric valves of the early 1960s, after some months of implantation, developed a smooth endothelial covering. Based on this observation, the Braunwald-Cutter valve was developed. This ball valve prosthesis was totally covered with fabric, including the struts. The silicone poppet was abraded by the fabric. Later, using a Pyrolyte ball, the fabric on the struts shredded. (Q) The Björk-Shiley prosthesis, beginning in 1969, was the first extensively used tilting disc prosthesis. The disc was held in place by two wire struts, one on each side of the disc. The disc used initially was made of the plastic Delrin, which would swell in a fluid medium and lock up. This was replaced with a Pyrolyte disc. After a period of time, the struts would fracture in some of the valves, releasing the disc. (R) The Lillehei-Kaster 1970 prosthesis contained a tilting disc, which was smooth on both surfaces and retained in place and through the disc excursions by means of two lateral struts. The seating was made of titanium and the disc of Pyrolyte. Some of the original patients in whom this prosthesis was used continue to do well. (S) The 1973 biconical disc Cooley-Cutter valve placed a Pyrolyte poppet at the equater of the housing.
The Annals of Thoracic Surgery  , DOI: ( /S (00) )

4. Fig 3
(T) The Wada-Cutter valve from 1966 was an early attempt to make a tilting disc prosthesis. In this case the Teflon disc contained two major notches matched to mating notches in the housing, which fixed the disc to the housing. Hemodynamically the valve worked well, however, it developed excessive wear at the hinge mechanism. (U) The St Jude heart valve was the first bileaflet valve to achieve major success beginning in Pyrolyte was used for the leaflets as well as the housing. (V) The Medtronic-Hall-Kaster valve was developed in 1976 and continues to be used. It Pyrolyte disc has a central perforation through which curved wire struts guide its course. (W) The Bjork-Shiley monostrut valve was developed to compensate for the weak support of the wire struts used previously. The two legged outflow strut was replaced with a single catch strut, machined in titanium as part of the housing. (X) The Omniscience valve was introduced in 1978 to replace the Lillehei-Kaster valve. The only change was to replace the extended struts with two tabs as the catch mechanism. This valve had a titanium housing and a Pyrolyte disc. The Omnicarbon Valve was introduced in 1984 and contains both disc and housing structures made of pyrolytic carbon. Both valves retain clinical usefulness.
The Annals of Thoracic Surgery  , DOI: ( /S (00) )